Placidium Nigrum
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Placidium Nigrum
''Placidium nigrum'' is a species of squamulose (scaley), ground-dwelling lichen in the family Verrucariaceae. It is found in Northwest China and the Tibetan Plateau, where it grows on sandy soil surfaces in semi-arid and arid regions. The lichen was formally described as new to science in 2022 by Tingting Zhang and Xinli Wei. The type specimen was collected from the Da Qaidam (Haixi Mongol and Tibetan Autonomous Prefecture), at an altitude of ; it has since been collected at altitude ranges between . The species epithet ''nigrum'' alludes to the black area surrounding the thallus that results from an aggregation of pycnidia ( asexual fruiting bodies). These abundant, tiny pycnidia occur both superficially on the thallus surface (''laminal'') and on the lobe edges (''marginal''). ''Placidium nigrum'' does not react with any of the standard chemical spot tests, and no lichen products were detected from the species using thin-layer chromatography Thin-layer chromatography ...
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Squamulose Lichen
A squamulose lichen is a lichen that is composed of small, often overlapping "scales" called squamules. If they are raised from the substrate and appear leafy, the lichen may appear to be a foliose lichen, but the underside does not have a "skin" (cortex), as foliose lichens do. Squamulose lichens are composed of flattish units that are usually tightly clustered. They are like an intermediate between crustose Crustose is a habit of some types of algae and lichens in which the organism grows tightly appressed to a substrate, forming a biological layer. ''Crustose'' adheres very closely to the substrates at all points. ''Crustose'' is found on rocks ... and foliose lichens. Examples of squamulose lichen include '' Vahliella leucophaea'', '' Cladonia subcervicornis'' and '' Lichenomphalia hudsoniana''. References Lichenology {{lichen-stub ...
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Thallus
Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms were previously known as the thallophytes, a polyphyletic group of distantly related organisms. An organism or structure resembling a thallus is called thalloid, thallodal, thalliform, thalline, or thallose. A thallus usually names the entire body of a multicellular non-moving organism in which there is no organization of the tissues into organs. Even though thalli do not have organized and distinct parts (leaves, roots, and stems) as do the vascular plants, they may have analogous structures that resemble their vascular "equivalents". The analogous structures have similar function or macroscopic structure, but different microscopic structure; for example, no thallus has vascular tissue. In exceptional cases such as the Lemnoideae, where ...
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Lichen Species
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.Introduction to Lichens – An Alliance between Kingdoms
. University of California Museum of Paleontology.
Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but are not s. They may have tiny, leafless branches (); flat leaf-like structures (

Verrucariales
Verrucariales is an order of ascomycetous fungi within the subclass Chaetothyriomycetidae of the class Eurotiomycetes. Although most of the Verrucariales are lichenised, the family Sarcopyreniaceae consists of 11 species of lichenicolous (lichen-dwelling) fungi. Phylogenomic analysis suggests that the divergence between the lichenized Verrucariales and nonlichenized Chaetothyriales The Chaetothyriales are an order of ascomycetous fungi in the class Eurotiomycetes and within the subclass Chaetothyriomycetidae. The order was circumscribed in 1987 by mycologist Margaret Elizabeth Barr-Bigelow. Families and genera , Species ... occurred about 131 million years ago. Genera of uncertain placement There are some genera in the Verrucariales that have not been placed with certainty into any family. These are: *'' Botryolepraria'' – 2 spp. *'' Gemmaspora'' – 1 sp. *'' Kalbiana'' – 1 sp. *'' Merismatium'' – 10 spp. References Ascomycota orders Lichen orders ...
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Thin-layer Chromatography
Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures. Thin-layer chromatography is performed on a sheet of an inert substrate such as glass, plastic, or aluminium foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminium oxide (alumina), or cellulose. This layer of adsorbent is known as the stationary phase. After the sample has been applied on the plate, a solvent or solvent mixture (known as the mobile phase) is drawn up the plate via capillary action. Because different analytes ascend the TLC plate at different rates, separation is achieved. It may be performed on the analytical scale as a means of monitoring the progress of a reaction, or on the preparative scale to purify small amounts of a compound. TLC is an analytical tool widely used because of its simplicity, relative low cost, high sensitivity, and speed of separation. TLC functions on the same principle as all chromatography: a com ...
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Lichen Product
Lichen products, also known as lichen substances, are organic compounds produced by a lichen. Specifically, they are secondary metabolites. Lichen products are represented in several different chemical classes, including terpenoids, orcinol derivatives, chromones, xanthones, depsides, and depsidones. Over 800 lichen products of known chemical structure have been reported in the scientific literature, and most of these compound are exclusively found in lichens. Examples of lichen products include usnic acid (a dibenzofuran), atranorin (a depside), lichexanthone (a xanthone), salazinic acid (a depsidone), and isolichenan, an α-glucan. Many lichen products have biological activity, and research into these effects is ongoing. Lichen products accumulate on the outer walls of the fungal hyphae, and are quite stable. Crystal deposits can be visualised using scanning electron microscopy. For this reason, even very old herbarium specimens can be analysed. The amount of lichen products i ...
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Spot Test (lichen)
A spot test in lichenology is a spot analysis used to help identify lichens. It is performed by placing a drop of a chemical on different parts of the lichen and noting the colour change (or lack thereof) associated with application of the chemical. The tests are routinely encountered in dichotomous keys for lichen species, and they take advantage of the wide array of lichen products produced by lichens and their uniqueness among taxa. As such, spot tests reveal the presence or absence of chemicals in various parts of a lichen. They were first proposed by the botanist William Nylander in 1866. Three common spot tests use either 10% aqueous KOH solution (K test), saturated aqueous solution of bleaching powder or calcium hypochlorite (C test), or 5% alcoholic ''p''-phenylenediamine solution (P test). The colour changes occur due to presence of particular secondary metabolites in the lichen. There are several other less frequently used spot tests of more limited use that are employed ...
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Asexual Reproduction
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent and thus the newly created individual is genetically and physically similar to the parent or an exact clone of the parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and eubacteria, bacteria. Many Eukaryote, eukaryotic organisms including plants, animals, and Fungus, fungi can also reproduce asexually. In vertebrates, the most common form of asexual reproduction is parthenogenesis, which is typically used as an alternative to sexual reproduction in times when reproductive opportunities are limited. Komodo dragons and some monitor lizards can also reproduce asexually. While all prokaryotes reproduce without the formation and fusion of gametes, m ...
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Pycnidia
A pycnidium (plural pycnidia) is an asexual fruiting body produced by mitosporic fungi, for instance in the order Sphaeropsidales ( Deuteromycota, Coelomycetes) or order Pleosporales (Ascomycota, Dothideomycetes). It is often spherical or inversely pearshaped ( obpyriform) and its internal cavity is lined with conidiophores. When ripe, an opening generally appears at the top, through which the pycnidiospore {{Short pages monitor [Baidu]  


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Botanical Name
A botanical name is a formal scientific name conforming to the '' International Code of Nomenclature for algae, fungi, and plants'' (ICN) and, if it concerns a plant cultigen, the additional cultivar or Group epithets must conform to the ''International Code of Nomenclature for Cultivated Plants'' (ICNCP). The code of nomenclature covers "all organisms traditionally treated as algae, fungi, or plants, whether fossil or non-fossil, including blue-green algae ( Cyanobacteria), chytrids, oomycetes, slime moulds and photosynthetic protists with their taxonomically related non-photosynthetic groups (but excluding Microsporidia)." The purpose of a formal name is to have a single name that is accepted and used worldwide for a particular plant or plant group. For example, the botanical name ''Bellis perennis'' denotes a plant species which is native to most of the countries of Europe and the Middle East, where it has accumulated various names in many languages. Later, the plant was intro ...
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Terricolous
A terricolous lichen is a lichen that grows on the soil as a substrate. An example is some members of the genus ''Peltigera ''Peltigera'' is a genus of approximately 100 species of foliose lichens in the family Peltigeraceae. Commonly known as the dog or pelt lichens, species of ''Peltigera'' are often terricolous (growing on soil), but can also occur on moss, trees, ...''. References Lichenology {{lichen-stub ...
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Haixi Mongol And Tibetan Autonomous Prefecture
Haixi Mongolian and Tibetan Autonomous Prefecture (; mn, ᠬᠠᠶᠢᠰᠢ ᠶᠢᠨ ᠮᠣᠩᠭᠣᠯ ᠲᠥᠪᠡᠳ ᠦᠨᠳᠦᠰᠦᠲᠡᠨ ᠦ ᠥᠪᠡᠷᠲᠡᠭᠡᠨ ᠵᠠᠰᠠᠬᠤ ᠵᠧᠦ; bo, མཚོ་ནུབ་སོག་རིགས་ཆ་བོད་རིགས་རང་སྐྱོང་ཁུལ་), locally also known as Qaidam Prefecture (mong. Qaidam; tib. Caindam; chin. Chaidamu), is an autonomous prefecture occupying much of the northern tier of as well as part of the southwest of Qinghai Province, China. It has an area of and its seat is Delingha. The name of the prefecture literally means "west of (Qinghai) Lake." Geladandong Mountain, the source of the Yangtze River, is located here. History After 1949, the People's Government of Dulan County was founded and the area was renamed Dulan Autonomous District (); in 1954, Dulan was renamed Haixi Mongol, Tibetan and Kazakh Autonomous District () and in 1955, Haixi Mongol, Tibeta ...
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